Manage your subscription

The ice age that never was

By Hazel Muir

THE romantic notion that early humans lived in harmony with their environment has taken quite a battering lately. Modern humans may have started eliminating other species right from the start&colon; our ancestors stand accused of wiping out megafauna – from giant flightless birds in Australia to mammoths in Asia and the ground sloth of North America – as they spread across the planet.

Even so, by around 6000 years ago there were only about 12 million people on Earth – less than a quarter of the current population of Great Britain. That’s a far cry from today’s 6.6 billion, many of us guzzling fossil fuels, churning out greenhouse gases and messing with our planet’s climate like there’s no tomorrow. So it may seem far-fetched to suggest that humans have been causing global warming ever since our ancestors started burning and cutting forests to make way for fields at least 7000 years ago.

Yet that’s the view of retired climate scientist William Ruddiman, formerly of the University of Virginia, Charlottesville. Ancient farmers were pumping climate-warming carbon dioxide and methane into the atmosphere long before recorded history began, he says. Far from causing catastrophe, however, early farmers halted the planet’s descent into another ice age and kept Earth warm and stable for thousands of years.

Hugely controversial

Could a few primitive farmers really have changed the climate of the entire globe? If you find this hard to believe, you’re not the only one. Ruddiman’s idea has been hugely controversial ever since he proposed it in 2003. “Most new ideas, especially controversial ones, die out pretty fast. It doesn’t take science long to …